Methods of making resealable packages, method and apparatus

ABSTRACT

Methods of making flexible packages having an openable and resealable interlocking closure from a continuous web of flexible film, the closure being formed transversely to the direction of film flow at the consumer preferred position across one end of the package during package formation at line speed. The system utilizes a converter device mounted atop or adjacent to standard packaging apparatus to form a small amount of the running packaging film into the resealable closure structure as an integral part of the film extending transversely to the long dimension of the package. The converter functions with both horizontal and vertical form/fill/seal wrapping machines and with overwrap packagers, and uses diverse packaging films. The package formation begins by feeding the plastic packaging film into the converter where the film is first automatically fanfolded across the entire width of the film to form a stack, the layers of which are immediately heat sealed together forming a multilayered semi-rigid strip of typically one half inch width extending completely across the film width in plane with the film. The number of folds in the stack varies depending on the thermoforming properties and thickness of the particular film being used. In one embodiment of the invention, the resealable locking feature is next thermoformed into the multilayered strip which then continues through the packaging machinery in the usual manner, encircling the product and passing through the end sealer where the package ends are sealed and cut, and the front and back film panels are pressed together closing the resealable locking feature.

This application is a divisional of application Ser. No. 08/861,576filed on May 22, 1997 now U.S. Pat. No. 5,944,425.

This invention relates generally to packaging systems, and moreparticularly to methods for making flexible packages having an openableand resealable interlocking closure from a continuous web of flexiblefilm, the closure being formed transversely to the direction of filmflow at the consumer preferred position across one end of the packageduring package formation at line speed.

BACKGROUND OF THE INVENTION

In the past, the methods of making reclosable flexible packages haveinvolved either the extrusion of the locking structure along with thefilm extending longitudinally in the direction of film extrusion alongthe opposite edges of the film, or by heat sealing a separately maderesealable closure structure to the package film. The first type ofpackage formation results in packages having the reclosable feature inthe consumer non-preferred position along the long edge of the package,while the second type of package formation results in packages which areexpensive to make because of the need to inventory and store rolls ofthe separate resealable closure structure for attachment to thepackaging film and the need to insure that the separately obtainedpackaging film and closure structure are made of compatible materials.

SUMMARY OF THE INVENTION

The package and system according to the invention are not so limitedbecause the system utilizes a novel converter device mounted atop oradjacent to standard packaging apparatus to form a small amount of therunning packaging film into the resealable closure structure as anintegral part of the film oriented in the consumer desired directionextending transversely to the long dimension of the package. Theconverter functions with both horizontal and vertical form/fill/sealwrapping machines and with overwrap packagers, and uses diverse doublesided heat seal packaging films such as polypropylene, polyester,polyvinyl chloride, high and medium density polyethylene, thermoplasticheat seal coated non-plastic films, and various film laminations.

The package formation begins by feeding the plastic film, as it unwindsfrom the storage roll, into the the converter where the film is firstautomatically layered by fanfolding across the entire width of the filmto form a stack. Layering other than by fanfolding to form a stack maybe utilized, but fanfolding is a convenient and economical method ofstack forming. The number of folds will vary depending on thethermoforming properties and thickness of the particular film beingused. Once folded the stacked layers are immediately heat sealedtogether forming a multilayered semi-rigid strip of typically one halfinch width extending completely across the film width in plane with thefilm. Next, in one embodiment of the invention, the resealable lockingfeature is thermoformed into the multilayered strip which then continuesthrough the packaging machinery in the usual manner, encircling theproduct and passing through the end sealer where the package ends aresealed and cut. Finally, as the package exits from the end sealer, thefront and back film panels are pressed together closing the resealablelocking feature.

In another embodiment of the invention the multilayered semi-rigid stripcarried by the packaging film is abraded on one surface to remove thethermoplastic heat seal coating and leave that surface of the stripuncoated, the film being then passed into the package forming apparatuswhere the product wrapping takes place. After emerging from the packageforming apparatus the package ends are sealed and the package resealablelocking feature is completed. The entire process takes place atpackaging line speed.

It is a primary object of the invention to provide novel methods ofmaking a flexible package having an openable and resealable interlockingclosure.

Another object of the invention is to provide novel methods of making aflexible package having an openable and resealable interlocking closurein which the closure is formed transversely to the direction of filmflow at the consumer preferred position across one end of the package.

A further object of the invention is to provide novel methods of makingpackages as aforesaid which are formed during the packaging operationrunning at line speed.

Yet a further object of the invention is to provide novel methods ofmaking packages as aforesaid in which the resealable interlockingclosure is integrally formed from layered together contiguous portionsof the packaging film during the packaging process and does not requirethat additional materials be added to the packaging film to form theresealable closure.

A still further object of the invention is to provide novel methods ofmaking packages as aforesaid in which the packages may be formed from avariety of packaging films such as polypropylene, polyester, polyvinylchloride, high and medium density polyethylene, and various filmlaminations.

Still another object of the invention is to provide novel methods ofmaking packages as aforesaid in which the resealable interlockingclosure is integrally formed from the packaging film by reverselyfanfolding the packaging film across its running width to form a stack,sealing together the reversely folded stack in plane with the film, andthermoforming the sealed stack into the resealable locking feature.

The foregoing and other objects of the invention will be more clearlyunderstood from a reading of the following description in conjunctionwith an examination of the appended drawings, wherein:

FIG. 1 is an isometric view of a package according to the inventionshowing the package end seals and the integrally formed resealablelocking feature;

FIG. 1a is a plan view of an alternative form of package according tothe invention showing the package end seals and the integrally formedresealable locking feature;

FIG. 2 is an enlarged cross sectional view through the resealableclosure and package end seal as would be seen when viewed along the line2--2 on FIG. 1;

FIG. 2a is a view similar to FIG. 2 but showing a modified form ofresealable closure;

FIGS. 3 and 4 respectively show the tearing off of the package endsealand the opening of the resealable closure of a package as in FIG. 1;

FIGS. 5 and 6 show progressive stages of opening the interlockingresealable package closure shown in FIG. 2;

FIG. 7 is a diagrammatic illustration of one form of apparatus for andmethod of formation of novel packages according to the invention,showing the stages of closure forming from the packaging film during thepackaging process;

FIG. 8 is an isometric view of the portion of the apparatus whichaccomplishes the fanfolding of the film;

FIGS. 9a through 9e are cross sectional views through the apparatus ofFIG. 8 showing the stages of formation of a fanfolded and sealed filmstack;

FIG. 10 is an isometric view of the portion of the apparatus which formsthe resealable locking feature;

FIG. 10a is a cross sectional view through the apparatus of FIG. 10 aswould be seen when viewed along the line 10a--10a on FIG. 10 showing areversely folded sheet of film positioned for forming a part of theresealable locking feature;

FIG. 11 is a cross sectional view through the apparatus of FIG. 10 aswould be seen when viewed along line 11--11 on FIG. 10;

FIGS. 12a through 12e are cross sectional views through the apparatus ofFIG. 10 as would be seen when viewed along the line 12--12 on FIG. 10showing the stages of thermoformation of another portion of theresealable closure locking feature;

FIG. 13 is an isometric view of the completely formed resealable lockingclosure feature in the film;

FIG. 14 is a cross sectional view through the package end sealing andclosure device for the resealable closure locking feature as would beseen when viewed along line 14--14 on FIG. 7;

FIG. 15 shows a modification of the apparatus shown in FIG. 7 in whichthe resealable locking feature is formed as the package is sealed;

FIG. 16 is an end view of the film scouring wheels seen in FIG. 15before the wrapping station; and

FIG. 17 is a cross sectional longitudinal view through the completedpackage, including the package end seals and resealable locking featureforming mechanisms as would be seen when viewed along line 17--17 onFIG. 15.

In the several figures, like elements are denoted by like referencecharacters.

Considering first FIGS. 1 and 1a, there are seen packages 20 and 20'respectively, each having respective package heat sealed end seals21a/21b and 21'a/b, and resealable package locking closures 22 and 22'.The packages are identical except for the shape of the resealablelocking closures, closure 22 being formed along a straight line, whileclosure 22' is formed along an arc. The straight line form of closurerequires less package length than the arcuate form, but the arcuate formprovides somewhat easier package opening because the opening force iseffectively applied to a shorter length of the closure. Both types areformed in the same way, as will be subsequently shown.

The resealable closures are formed during the package making processfrom multiple reversely fanfolded layers of the film from which thepackages are made, as best seen in the enlarged cross-sectional views ofFIGS. 2 and 2a, to which attention should be now directed. Theinternested closure sections of FIG. 2a are seen to be of triangularcross-section with the open base legs segments in horizontal alignment,whereas the closure sections 22a and 22b of FIG. 2 are seen to be formedwith the open base legs angled inwardly downward toward one another inan arrowhead shape instead of in horizontal disposition. This angledorientation of the base legs results in easier package opening andreclosing. In FIG. 2 the upper film portion 23 of the package 20 is seento be reversely folded into three layers 23a, 23b, and 23c forming theouter section 22a of the closure 22, with the lower film portion 24being similarly folded into three layers 24a, 24b, and 24c forming theinner section 22b of the closure 22. Three layers are shown forillustration, but it will be understood that more layers, such as fiveor even seven, may be used as the package and film characteristicsdetermine. The same arrangement is shown in the closure form of FIG. 2a.

FIGS. 3 through 6 illustrate the opening of the package 20 by firsttearing off the end seal 21b adjacent to the closure 22 as shown in FIG.3, and opening the resealable locking closure 22 by separating the outerand inner sections 22a and 22b as shown in FIG. 4. The separationprocess is illustrated in FIGS. 5 and 6 where the outer and innersections 22a and 22b are seen in FIG. 5 being respectively expanded andcompressed as the inner section 22b is pulled out of the outer section22a, and springing back to their static state conditions as illustratedin the completely separated showing of FIG. 6.

FIG. 7 is a diagrammatic showing of one form of apparatus for producingfinished packages as shown in the preceding Figures. Film 25 from a roll26 of heat sealable packaging film is spooled off and fed around roller27 and between rollers 28 to the film fanfolding device 29 where atpackage length intervals the film is multiple folded and heat sealedinto approximately half inch width strips (stack) 30 extending fullywidthwise of the running film. To accomplish this the film 25 is eithermade of thermoplastic material or is thermoplastically coated. The filmthen passes through the resealable closure forming device 31 where thestrips 30 are heat and pressure formed into the resealable closures 22,passes around the rollers 32 and into the packaging machine 33 where theitems 34 to be packaged are wrapped, and emerges for end sealing,package cutting, and interlocking engagement of the resealable lockingclosure by the device designated generally as 35, being thereaftercarried away for packing for shipment by conveyor 36.

The fanfolding device 29 and the process of forming the film 25 toinclude the heat sealed fanfolded strip 30 are shown in detail in FIGS.8 and 9, the position of the apparatus of FIG. 8 being that shown in theoperating cycle position of FIG. 9c. The device 29 essentially consistsof, a pair of fanfolding plates 37 having window slots 38, the platesbeing synchronously shiftable toward and away from one another inslightly separated parallel planes, upper and lower film clamping guiderods 39, and heating bars 40 carried on the guide bars 39. The film 25moves from right to left between the plates 37 as shown by arrows 41 inFIG. 9a. As shown in FIG. 9b by the arrows 42, the plates 37 are shiftedtoward one another into overlapping position to form a three layerfanfold of film 25 with the windows 38 of the plates 37 verticallyaligned. Next, as shown in FIG. 8 and in FIG. 9c by the arrows 43, thefilm clamping guide rods are shifted toward one another through thewindows 38 to clamp the three layers of film together. As shown in FIG.9d by arrows 44, the plates 37 are retracted away from one another,while as shown by arrows 45 the heating bars 40 are shifted toward oneanother and into engagement with the upper and lower outer surfaces ofthe fanfolded film strip to seal the layers together into the heatsealed strip 30.

Finally, as shown by arrows 46 in FIG. 9e, the rods 39 and heating bars40 are retracted, and the strip 30 moves out of the fanfolding device onits way to the device 31 for formation of the resealable closure parts22a and 22b, as seen in FIGS. 7 and 10 through 13. It should beunderstood that during the course of formation of the strip 30 theentire apparatus 29 moves in the direction of motion of the film 25 andthen retracts to its initial position in preparation for the next cycleof strip formation, as shown by the arrow 47. Similarly, it is to beunderstood that during the cycle of formation of the resealable closureparts 22a and 22b from the strip 30 the entire apparatus 31 moves in thedirection of motion of the film 25 and then retracts to its initialposition in preparation for the next cycle, as shown by the arrow 48.

As best seen in FIGS. 10 through 13, the device 31 includes an uppersection 31a and a lower section 31b, which are respectively providedwith heaters 49a and 49b, and with vacuum manifold fittings 50a and 50bwhich connect a selectively actuatable vacuum source to the vacuummanifolds 51a and 51b. Upper section 31a is provided with a triangulardepending central anvil 52a, and lower section 31b is provided with apair of spaced apart triangular end sections anvils 52b, all of theanvil sections being longitudinally aligned. Formed in the upper section31a in apposition to the end anvils 52b of the lower section 31b are apair of complementally shaped triangular recesses 53a, while formed inthe lower section 31b in apposition to the central anvil 52a of theupper section 31a is a complementally shaped triangular recess 53b. Thestructure is completed by aligned coplaner pairs of upper section endforming plates 54 and a pair of lower section central forming plates 54,the plates of each pair being disposed for reciprocation toward and awayfrom one another with all plates being actuated simultaneously.

Formation of the resealable closure parts 22a is illustrated in FIG. 12,which, it is to be understood, while showing the formation of an endpart 22a also shows the operating sequence for formation of the centralpart 22b by the structure of FIG. 10a. As the heat sealed strip 30 comesinto position within the forming device 31 as shown in FIG. 12a, theforming device starts to move longitudinally with the film 25 and theforming sequence is initiated. As shown in FIG. 12b, the heated upperand lower forming sections 31a and 31b move toward one another and mate,heat forming the strip 30 into the recesses 53a and 53b where the stripis retained in position by vacuum drawn through the manifolds 51a and51b. The anvils 52a, and 52b as shown in FIG. 12c, then retract whilethe vacuum continues to hold the strip in the recesses. The formingplates 54 of each pair, as seen in FIG. 12d, then move toward oneanother and shape the inturned legs into the heat softened strip 30.Finally, as seen in FIG. 12e, the forming plates are retracted and thevacuum is released, thereby releasing the formed resealable closure. Theforming device is then retracted to its starting position in preparationfor forming the next closure. The closure formed running film is shownin FIG. 13. The film 25 with its formed closures 22a and 22b moves intothe packaging machine 33 along with the items 34 to be packaged, andemerges as a wrapped but unsealed package unseparated from the precedingand succeeding packages.

The completion of the packaging by sealing and separation takes place atthe sealing station sealing and locking device 35, shown in FIG. 7 andin the enlarged cross sectional detail of FIG. 14, to which referenceshould now be made. The first wrapped product 55 emerges from thepackaging machine 33 and passes into the sealer 35 where the leadingportion of the film passes over the lower heat sealing bars 55 and 56,the upper heat sealing bars 57 and 58 descending to form the oppositeend seals 21a and 21b shown in FIG. 1, followed closely by the descentof the cutting bar 59 which severs the seals 21a/21b from one another.The sealing device 35 is then opened to release the just formed endseals and allow the partially completed package 55 to pass through. Thisfirst seal 21b formed by the sealer bars 56/58 is discarded as scrapsince it is not part of a package, the seal 21 a formed by the sealerbars 55/57 becoming the leading end seal of what will become the firstpackage 20.

Consider now that the partially completed first package, originallydesignated as 55 In FIG. 14 and being now designated 20, has passedcompletely through the open sealing device 35 so that the part of thepackaging film carrying the closures 22a and 22b at the trailing end ofthe open package is disposed between the resilient upper and lowerpressure blocks 61 and 62 of the locking device 35 with a portion offlat film extending to the left between the sealer bars 55-58 to thebeginning of the next wrapped product 55. The sealing device 35 is againclosed so that a new set of end seals 21a and 21b are formed andseparated, and simultaneously the upper and lower pressure blocks 61 and62 are moved toward one another to press the inside closure part 22binto latching engagement inside the outside closure part 22a. Thesealing device 35 is again opened to release the just formed end sealsand allow the separated completed package 20 to be moved off fordisposition and permit the next partially completed package 55 to passthrough. This sequence repeats and produces a continuous line ofpackaged products.

A second embodiment of a method and apparatus for forming the packages20 is shown in FIGS. 15 to 17. The apparatus of FIG. 15 is similar tothat of FIG. 7 in many aspects as shown by the same reference charactersapplied to common elements. The film 25 is spooled off of roll 26 andinto the fanfolded strip forming device 29 where heat sealed multilayerstrips 30 are sequentially formed as previously described. These stripsthen proceed to an abrader, generally designated as 63, where theundersurface of the strip 30 is abraded to remove the thermoplastic heatseal coating and leave that surface of the strip uncoated. As seen inFIGS. 15 and 16 the abrader 63 includes a pair of abrading wheels 64driven by motors 65 supported on a carrier bar 66. The carrier bar 66reciprocates transversely to the running length of the film to treat theentire surface of the strip 30, as shown by arrow 67, and also moveslongitudinally with the film for a distance sufficient to complete thestrip abrasion. Upon completion of a strip treatment the abrader movesdownward out of engagement with the film and returns to its startingplace to engage the next strip. The film is then passed into the packageforming apparatus 33 where product wrapping takes place. After emergingfrom the package forming apparatus the package ends are sealed by asealing device 69, and at the same time the package resealable lockingfeature is completed from the strip 30 by a closure former 70, all asbest seen from FIGS. 15 and 17. A wrapped product 71 carrying strips 30emerges from the packaging machine 33 and passes to a position betweenthe sealing device 69 and the closure former 70. The upper and lowerheat sealing bars 72 and 73 move toward one another to heat seal theends of adjacent packages to form the opposite end seals 21a and 21bshown in FIGS. 1 and 17, followed closely by the descent of the cuttingbar 74 which severs the seals 21a/21b of the adjacent packages from oneanother. As seen in FIG. 15, the strips 30 have been wrapped duringpackaging so that each strip is disposed in two layers, one above theother with the abraded surfaces in contact. When the strip 30 is heatformed into the resealable closure 22 by the closure former 70 in themanner already described in connection with the apparatus of FIG. 10,the facing abraded surfaces of strips 30 remain unsecured to one anotherso that they may be subsequently separated. This sequence repeats andproduces a continuous line of packaged products.

Having now described the invention in connection with particularlyillustrated embodiments thereof, it will be understood thatmodifications and variations of the invention may now occur from time totime to those normally skilled in the art without departing from theessential scope or spirit of the invention, and accordingly it isintended to claim the invention both broadly and specifically asindicated in the appended claims.

What is claimed is:
 1. A method of making a resealable interlockingclosure for a flexible resealable package, consisiting of the stepsof,a) transporting in lengthwise direction a web of flexible packagingmaterial of selected width and indeterminate length, b) fanfolding saidweb in the direction of the running length to form a stack of packagingmaterial extending widthwise of the web, c) securing together thefanfolded layers of said stack of packaging material, d) formingdifferent sections of said stack into inner and outer portions of aresealable interlocking closure.
 2. The method of making a resealableinterlocking closure for a flexible resealable package as set forth inclaim 1 wherein said flexible packaging material has thermoplasticproperties, and wherein the step of securing together said fanfoldedlayers of said stack of packaging material is a step of heat sealing. 3.The method of making a resealable interlocking closure for a flexibleresealable package as set forth in claim 1 wherein said flexiblepackaging material has thermoplastic properties, and wherein the stepsof securing together said fanfolded layers of said stack of packagingmaterial and forming said interlocking closure are both steps of heatsealing.
 4. The method of making a resealable interlocking closure for aflexible resealable package as set forth in claim 1 wherein saidpackaging material has surface thermoplastic heat sealing properties,and further including between steps c) and d) the further step ofabrading one of the outer layers of said fanfolded layers of said stackof packaging material to remove its said thermoplastic heat sealingproperties.
 5. The method of making a resealable interlocking closurefor a flexible resealable package as set forth in claim 1 wherein saidstep of fanfolding said web into a stack of packaging material fanfoldssaid stack into at least three layers.
 6. The method of making aresealable interlocking closure for a flexible resealable package as setforth in claim 1 wherein said flexible packaging material comprises aflexible substrate coated with a thermoplastic material.
 7. The methodof making a resealable interlocking closure for a flexible resealablepackage as set forth in claim 1 wherein said step of forming differentsections of said stack into inner and outer portions of a resealableinterlocking closure includes the steps of forming one of said inner andouter portions as a continuous length and initially forming the other ofsaid inner and outer portions as two lengths separated by saidcontinuous length.
 8. The method of making a resealable interlockingclosure for a flexible resealable package as set forth in claim 1wherein said step of forming different sections of said stack into innerand outer portions of a resealable interlocking closure includes thestep of forming said inner portion as a continuous length and initiallyforming said outer portion as two lengths separated by said innerportion.
 9. The method of making a resealable interlocking closure for aflexible resealable package as set forth in claim 1 wherein said step offorming different sections of said stack into inner and outer portionsof a resealable interlocking closure includes the steps of forming saidinner portion as a continuous length and initially forming said outerportion as two lengths separated by said inner portion.
 10. The methodof making a resealable interlocking closure for a flexible resealablepackage as set forth in claim 3 wherein said step of forming differentsections of said stack into inner and outer portions of a resealableinterlocking closure includes the steps of forming said inner portion asa continuous length and initially forming said outer portion as twolengths separated by said inner portion.
 11. The method of making aresealable interlocking closure for a flexible resealable package as setforth in claim 5 wherein said step of forming different sections of saidstack into inner and outer portions of a resealable interlocking closureincludes the steps of forming said inner portion as a continuous lengthand initially forming said outer portion as two lengths separated bysaid inner portion.
 12. The method of making a resealable interlockingclosure for a flexible resealable package as set forth in claim 6wherein said step of forming different sections of said stack into innerand outer portions of a resealable interlocking closure includes thesteps of forming said inner portion as a continuous length and initiallyforming said outer portion as two lengths separated by said innerportion.
 13. The method of making a resealable interlocking closure fora flexible resealable package as set forth in claim 6 wherein the stepsof securing together said fanfolded layers of said stack of packagingmaterial and forming said interlocking closure are both steps of heatsealing.
 14. The method of making a resealable interlocking closure fora flexible resealable package as set forth in claim 13 wherein said stepof forming different sections of said stack into inner and outerportions of a resealable interlocking closure includes the steps offorming said inner portion as a continuous length and initially formingsaid outer portion as two lengths separated by said inner portion. 15.The method of making a flexible package comprising a package body, aresealable interlocking closure, and end seals at opposite ends of thepackage, consisting of the steps of:a) transporting in lengthwisedirection a web of flexible packaging material of selected width andindeterminate length, b) fanfolding said web in the direction of therunning length at package length intervals to form a stack of packagingmaterial extending widthwise of the web, c) securing together thefanfolded layers of each of said stacks of packaging material, d)wrapping a product within that portion of the flexible packagingmaterial extending between a sequential pair of said secured stacks ofpackaging material to define a package length, e) folding into upper andlower apposed positions different sections of the said secured stack ofpackaging material adjacent one end of the defined package length, f)sealing and severing from one another adjacent ends of successivepackages, g) forming a resealable interlocking closure having inner andouter portions from the said apposed different sections of the saidsecured stack of packaging material adjacent one end of the definedpackage length, and h) pressing the inner portion into the outer portionof the resealable interlocking closure.
 16. The method of making aflexible package as set forth in claim 15 wherein steps f) and g) arecarried out substantially simultaneously.
 17. The method of making aflexible package as set forth in claim 15 wherein steps f), g) and h)are carried out substantially simultaneously.
 18. The method of making aresealable interlocking closure for a flexible resealable package as setforth in claim 15 wherein said packaging material has surfacethermoplastic heat sealing properties, and further including betweensteps c) and e) the further step of abrading the facing surfaces of saidapposed portions of said stack of packaging material to remove therefromsaid thermoplastic heat sealing properties.